FROM AROUND THE STATE

ISSUE 11  July 13, 2000

1 wheat midge per 4-5 wheat heads

When to scout? At night, after 9:00 PM; light wind <6mph; temperature above 60^oF

Flight Reports: Wheat midge flight has been HEAVY (1 midge per 4-8 heads) in the Divide
County - Noonan-Crosby area as expected. There are scattered reports of MODERATE
levels (1 midge per 5-15 heads) from the Glenburn-Deering area (southern Renville and
Bottineau Counties) and Berthold-Kenmare area (Ward County). Flights are also LOW in the
northern half of eastern Renville and western Bottineau Counties. Thanks to the many contributors!

For the Degree Day (DD) Model, 50% emergence of the females is by 1450 DD and 90%
emergence by 1600 DD, using a 40^"F Base. The following insect DD have been accumulated as
of July 11, 2000: Rollette Co., Rolla = 1423, Burke Co., Columbus = 1436, Bottineau Co.,
Bottineau = 1518, McHenry Co., Towner = 1601; Renville Co., Mohall = 1538, McLean Co.,
Turtle Lake = 1667, Ward Co., Minot = 1666, and Williams Co., Williston = 1768 (Source: NDAWN).

Chemical Control:
    Lorsban 4e-sg and penncap-m (supplemental label) are labeled for control of wheat
midge in small grains this year. The rate of Lorsban is 1 fluid pint per acre and Penncap-M
is 2-3 pints per acre. The estimated cost is $5.00 per acre for 1 pint of Lorsban, and $7.00 per
acre for 2 pints of Penncap-M. Comparison of efficacy of the two insecticide in 1999 and 1997
(source: M. Weiss) tests have shown no significant differences between Lorsban and Penncap-M.
Midge infestation pressure in these test plots was low. Penncap-M did have lower numbers of
midge larvae per head than Lorsban when a phase wetting agent was added to the tank. Both
Lorsban and Penncap-M are in the same Insecticide Class Organophosphates, and should act
as contact and stomach poison.

    Some growers are reducing the rate of lorsban to ½ pint or less per acre. This will provide
a "knock down" affect for wheat midge and aphids in LOW population densities. But, control
will be limited in areas with moderate to heavy pressures. In 1999 studies, the number of midge
larvae per head were higher using the ½ pint rate compare to the full rate 1 pint, with a standard
nozzle XR 8001. However, differences in midge control between the two rates were minimized
when a twin-jet 8002 nozzle was used instead of the XR 8001. This suggests that the 8002
nozzle may provide better coverage and protection at the lower rate.

    Application Timing: The best time to treat is when 75% heads have emerged from the boot
to early flowering, and spray in the evening (preferred) or early morning. When spraying by air,
apply a minimum of 2 gallons per acre and 10 gallons per acre by ground. In a 1999 timing study, the
number of wheat midge larvae were reduced in spray applications applied at 80% heading as well as
early flowering (<25% bloom) to mid flowering (>25-50%), using Lorsban.

    Many growers are TANK MIXING WITH A FUNGICIDE (i.e., Folicur, Tilt) for
Fusarium head blight (scab) and leaf diseases (tan spot, Septoria) control. Research has
shown a synergistic effect, higher yields, when Lorsban and Folicur, for example, are tank mixed.
Remember for good coverage and control with the foliar fungicide, it is recommended to
USE 5 GALLONS OF WATER PER ACRE BY AIR (not 2 gallons) and 15 GALLONS
OF WATER PER ACRE BY GROUND. Application timing is best in the early flowering
stage (Feekes 10.5) for scab control. Use of a surfactant, Induce or Silwet, also improved
efficacy. Please see "Application of Fungicide for Suppression of Fusarium Head Blight
(Scab), AE-1148 on NDSU internet site.

Note: The 1999 WHEAT MIDGE TRIALS mentioned above are available of the internet at
the North Central Research Extension Center, Minot website. Click on Pest Summaries.

            http://www.ag.ndsu.nodak.edu/minot

Janet J. Knodel
Area Extension Specialist Crop Protection
North Central Research and Extension Center
Minot, ND

South-Central ND

    Total rainfall as recorded at NDAWN sites in south-central ND during July 5 to 11 ranged
from 1.04 inches at Dazey to 2.55 inches at McLeod. The rain was needed in Emmons and portions
of neighboring counties, but the balance of this region did NOT need more moisture. On July 11,
estimated daily water use of wheat emerged May 1, corn emerged May 15, soybean emerged
May 29, and sunflower emerged June 5 ranged from 0.04 inches in the north to 0.19 inches in the south.

    Cool-season crop condition has deteriorated due to generally excessive soil moisture, lodging, and
disease. The majority of the region’s small grain crop is in various seed-fill stages. Winter cereal and
barley harvest will begin late this month. Flowering is nearly complete with fall- and early spring-seeded
canola and some swathing may occur the last week of July. Warm-season crops are rapidly developing.

    Leaf spot disease (tan spot, leaf rust, and Septoria in wheat; spot and net blotch in barley) severity is
rapidly increasing. The NDSU foliar disease forecasting model for the Carrington site indicated potential
for tan spot and leaf rust every day during July 2 to 11. Conditions for scab in small grain and sclerotinia
in canola continue to be very favorable and both diseases are beginning to being found. Aster yellows is
being found in canola. Ascochyta blight has appeared in chickpea in McIntosh County.

    Accumulated degree days (DD) for orange wheat blossom midge as of July 11 ranged from 1605
units at Harvey to 1956 units at Oakes. Midge emergence has peaked throughout the region and
populations continue to appear below economic levels. However, continue scouting wheat fields that
are at risk until 1800 DD have been reached. Black light trap counts for European corn borer at
Carrington have recently increased and monitoring for this insect should begin. Scattered canola
plants can be found with damaging populations of aphids.

Greg Endres
Area Extension Specialist/Cropping Systems
Carrington Research and Extension Center
gendres@ndsuext.nodak.edu